High-speed and high-current density C60 diodes

Abstract

A high-performance organic diode is demonstrated by using ${\mathrm{C}}_{60}$ sandwiched between a cathode and an anode using metals with different diffusivity and donor ability. In this letter, copper (Cu) and aluminum (Al) are selected as the cathode and anode, respectively. ${\mathrm{C}}_{60}$ is used as the organic electron-acceptor for its high stability and high carrier mobility. The as-prepared diode shows poor performance. However, after heat treatment, the ${\mathrm{Cu/C}}_{60}$ interface becomes an Ohmic contact through Cu diffusion and charge-transfer processes, allowing highly efficient electron injection from the Cu electrode. On the other hand, a rectified ${\mathrm{C}}_{60}/\mathrm{Al}$ contact is formed, prohibiting efficient electron injection from the Al electrode into ${\mathrm{C}}_{60}.$ Hence, a high-performance organic diode is formed through a heat treatment process, not by the selection of metals with different work functions. Due to the high mobility of ${\mathrm{C}}_{60},$ the device shows megahertz frequency response, and it can also handle rather high current density (363 ${\mathrm{A/cm}}^2$ at 2.4 V). This opens the way for the formation of high-performance organic electronic devices.